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Cutting Soot, Methane Will Benefit Climate Less Than Predicted: Study

Reducing greenhouse gas emissions will do more to stem global warming, researchers say

MONDAY, Aug. 12 (HealthDay News) -- Reducing emissions of only soot and methane won't do as much to limit global warming as some previous research has suggested, according to a new study.

Instead, a focus on reducing greenhouse gas emissions is needed to counter global warming by 2050, according to the report, which was published Aug. 12 in the Proceedings of the National Academy of Sciences.

"Cutting back only on soot and methane emissions will help the climate, but not as much as previously thought," study author Steve Smith, a climate researcher at the U.S. Department of Energy's Pacific Northwest National Laboratory, said in a laboratory news release.

"If we want to stabilize the climate system, we need to focus on greenhouse gases such as carbon dioxide, nitrous oxide and methane," he said. "Concentrating on soot and methane alone is not likely to offer much of a shortcut."

Some previous studies have suggested that reducing soot and methane emissions could cut human-caused global temperature increases by an average of about 0.5 degrees Celsius by 2050. As a result, an international coalition was formed to reduce these pollutants.

But soot and methane remain in the atmosphere only for relatively short periods of time -- a few weeks for soot and up to a decade for methane -- while carbon dioxide remains in the atmosphere for 1,000 years or more, Smith and colleagues said.

Using a computer model, they concluded that cutting soot and methane emissions would reduce temperature increases by an average of only 0.16 degrees Celsius by 2050, which is far less than predicted in previous studies. Cutting emissions of carbon dioxide and other greenhouse gases would reduce temperature increases by 0.27 degrees Celsius by 2050.

"Focusing on soot and methane may be worth targeting for health reasons, as previous studies have identified substantial health benefits from reducing those emissions," Smith said. "To stabilize the global climate, however, the focus needs to be on carbon dioxide and other greenhouse gases."